Bacterial pneumonia in horses associated with Escherichia coli infection: report of five cases / [Pneumonia bacteriana em equinos associada à infecção por Escherichia coli: relato de cinco casos]

Respiratory diseases have a major impact on sport horses and are often cited as the second most common reason for loss of training days and significant veterinary costs. Adult horses most commonly develop pneumonia when bacteria aspirated from the environment, nose, or oropharynx reach the lower airways and overwhelm the pulmonary defense mechanisms. This article report five cases of bacterial pneumonia in horses associated with infection by Eschericia coli. Five Quarter horses, three males and two females, with ages varying from 5 to 12 years, were examined for diagnosis of respiratory disease characterized by apathy, cough and lack of appetite. Auscultation of the thorax revealed increased harsh breath sounds dorsally, crackles, wheezes, and dullness of respiratory sounds ventrally. Manipulation of the trachea and larynx induced cough. Culture results were positive for Escherichia coli. The therapeutic protocol consisted of anti-inflammatory, antibiotic therapy, and supportive care. Flunixin meglumine was administered intravenously at 24-hour intervals over eight days. Ceftiofur sodium was prescribed intramuscularly, q.d., for 15 days. Horses were clinically monitored daily until complete remission of clinical signs. None of the animals relapsed, and all returned to routine athletic activities.

As doenças respiratórias têm um grande impacto nos cavalos de esporte e são frequentemente citadas como o segundo motivo mais comum para a perda de dias de treinamento e custos veterinários significativos. Os cavalos adultos desenvolvem mais comumente pneumonia quando bactérias aspiradas do ambiente, do nariz ou da orofaringe alcançarem as vias aéreas inferiores e sobrecarregam os mecanismos de defesa pulmonar. Este artigo tem como objetivo relatar cinco casos de pneumonia bacteriana em cavalos, associados à infecção por Eschericia coli. Cinco cavalos da raça Quarto de Milha, três machos e duas fêmeas, com idades variando de cinco a 12 anos, foram examinados para diagnóstico de doença respiratória caracterizada por apatia, tosse e falta de apetite. A auscultação do tórax revelou aumento dos sons respiratórios ásperos dorsalmente, crepitação, sibilos e abafamento dos sons respiratórios ventralmente. Manipulação da traqueia induziu tosse. Os resultados da cultura foram positivos para Escherichia coli. O protocolo terapêutico consistiu em anti-inflamatório, antibioticoterapia e cuidados de suporte. Flunixina meglumina, na dose de 1mg/kg, foi administrada, por via intravenosa, em intervalos de 24 horas ao longo de oito dias, enquanto ceftiofur sódico, na dose de 2,2mg/kg, por via intramuscular, q.d., foi administrado durante 15 dias. Os cavalos foram monitorados clinicamente, todos os dias, até a remissão completa dos sinais clínicos. Nenhum dos animais apresentou recidiva, e todos retornaram às atividades atléticas de rotina.

Oxidative stress, ceruloplasmin and neopterin biomarkers in dromedary camels with clinical endometritis.

The purpose of this study is to investigate the role of some oxidative stress (OS), ceruloplasmin (Cp), and neopterin (NPT) as diagnostic biomarkers for dromedary camels endometritis as well as to explore the impact of ceftiofur treatment on endometritis. Camels were categorized into two groups; healthy control group (n = 20) and endometritis group (n = 60). She-camels with clinical signs of endometritis (CE) received 6.6 mg/kg BW of ceftiofur (i/m). On days 7, and 14, she-camels were evaluated and clinical cure or failure to cure was determined. The comparison of the groups for OS demonstrated that endometritis caused an increase in serum malondialdehyde (sMDA), Cp, and NPT levels (P<0.05), but decreased serum levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) (P<0.05). The most prevalent pathogens involved in the etiology of CE are Arcanobacterium pyogenes, Streptococcus pyogenes, and Staphylococcus aureus. All examined biomarkers demonstrated a high degree of recognition between CE camel and healthy controls (the area under the curve (AUC) was 95.9 for NPT). A higher proportion of camels with CE that were treated with ceftiofur (90%, P<0.0001) showed clinical cure by the first dose, while 10% required a second dose. In conclusion, CE causes increased oxidative reactions and decreased antioxidant defense competence. Subsequently, the alteration in that balance that was represented by the biomarkers of OS could be beneficial for clinical practice and basic clinical research. Additionally, all trials demonstrated the efficacy of ceftiofur for the treatment of CE in she-camel.

Oxidative stress, ceruloplasmin and neopterin biomarkers in dromedary camels with clinical endometritis

The purpose of this study is to investigate the role of some oxidative stress (OS), ceruloplasmin (Cp), and neopterin (NPT) as diagnostic biomarkers for dromedary camels endometritis as well as to explore the impact of ceftiofur treatment on endometritis. Camels were categorized into two groups; healthy control group (n = 20) and endometritis group (n = 60). She-camels with clinical signs of endometritis (CE) received 6.6 mg/kg BW of ceftiofur (i/m). On days 7, and 14, she-camels were evaluated and clinical cure or failure to cure was determined. The comparison of the groups for OS demonstrated that endometritis caused an increase in serum malondialdehyde (sMDA), Cp, and NPT levels (P<0.05), but decreased serum levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) (P<0.05). The most prevalent pathogens involved in the etiology of CE are Arcanobacterium pyogenes, Streptococcus pyogenes, and Staphylococcus aureus. All examined biomarkers demonstrated a high degree of recognition between CE camel and healthy controls (the area under the curve (AUC) was 95.9 for NPT). A higher proportion of camels with CE that were treated with ceftiofur (90%, P<0.0001) showed clinical cure by the first dose, while 10% required a second dose. In conclusion, CE causes increased oxidative reactions and decreased antioxidant defense competence. Subsequently, the alteration in that balance that was represented by the biomarkers of OS could be beneficial for clinical practice and basic clinical research. Additionally, all trials demonstrated the efficacy of ceftiofur for the treatment of CE in she-camel.(AU)

Efficacy Prediction of Four Pharmaceutical Formulations for Intramammary Administration Containing Aloe vera (L.) Burm. f. Combined With Ceftiofur or Cloxacillin in Lactating Cows as an Alternative Therapy to Treat Mastitis Caused by Staphylococcus aureus.

Synergy or additive effect between Aloe vera (L.) Burm.f. and beta-lactam (ß-lactam) antibiotics has been reported against Staphylococcus aureus, one of the most important etiological agents of cow mastitis. The goal of the present study was to predict the efficacy of intramammary formulations containing the Aloe vera gel extract in the combination with cloxacillin or ceftiofur at low concentrations in lactating cows as an alternative therapy. Each quarter of 20 healthy Holstein Friesian lactating cows were treated with a single dose of one of the following formulations, corresponding to one of these treatment groups: A1, A2, A3, and A4. A1 and A2 contained cloxacillin at 0.25 and 0.5 mg/ml, whereas A3 and A4 contained ceftiofur 0.25 and 0.5 mg/ml, respectively. In addition, all formulations contained 600 mg/ml of an alcoholic extract of Aloe vera. Milk samples were taken at predefined time points. Antibiotics and aloin (active compound of Aloe vera) concentrations were assessed by liquid chromatography mass spectrometry system (LC-MS/MS). Pharmacokinetic profiles were obtained, and the efficacy index, the fraction of dosing interval in which the antimicrobial concentration remains above the minimum inhibitory concentrations (MICs) (T > MIC) for each formulation, was calculated considering MIC values against Staphylococcus aureus ATCC 29213 as obtained for the combination Aloe vera + antibiotic and aloin concentration in the extract. Mammary gland safety assessment was performed for each combination. Values of the main efficacy index for this study, T > MIC (h) for Aloe vera were 23.29, 10.50, 27.50, and 13.89, whereas for cloxacillin or ceftiofur were 19.20, 10.9, 19.74, and 15.63, for A1, A2, A3, and A4, respectively. Only A1 and A3 reached aloin and antibiotic recommended values as predictors of clinical efficacy for cloxacillin, ceftiofur, and aloin (50, 70, and 60%, respectively), assuming a dose interval of 24 h. The efficacy index values obtained suggest that A1 and A3 might be an effective therapy to treat bovine mastitis caused by S. aureus after a single dose. Nevertheless, further trials in S. aureus mastitis clinical cases are mandatory to confirm the efficacy of Aloe vera formulations.

A non-inferiority study evaluating a new extended-release preparation of tilmicosin injected subcutaneously vs. ceftiofur administered intramammary, as dry-cow therapy in Holstein Friesian cows.

BACKGROUND: A new, extended long-acting tilmicosin (TLAe) preparation was tested against intramammary ceftiofur (CEF) using a non-inferiority trial model during dry-cow therapy (DCT) in a farm with high bovine population density and deficient hygiene application. OBJECTIVES: To evaluate the possibility that TLAe administered parenterally can achieve non-inferiority status compared to CEF administered intramammary for DCT. METHODS: Cows were randomly assigned to TLAe (20 mg/kg subcutaneous; n = 53) or CEF (CEF-HCl, 125 mg/quarter; n = 38 cows) treatment groups. California mastitis testing, colony-forming unit assessment (CFU/mL), and number of cases positive for Staphylococcus aureus were quantified before DCT and 7 d after calving. A complete cure was defined as no bacteria isolated; partial cure when CFU/mL ranged from 150 to 700, and cure-failure when CFU/mL was above 700. RESULTS: TLAe and CEF had overall cure rates of 57% and 53% (p > 0.05) and S. aureus cure rates of 77.7% and 25%, respectively (p < 0.05). The pathogens detected at DCT and 7 days after calving were S. aureus (62.71% and 35.55%), Staphylococcus spp. (22.03% and 35.55%), Streptococcus uberis (10.16% and 13.33%), and Escherichia coli (5.08% and 15.55%). Non-inferiority and binary logistic regression analyses revealed a lack of difference in overall efficacies of TLAe and CEF. Apart from S. aureus, S. uberis was the predominant pathogen found in both groups. CONCLUSIONS: This study is the first successful report of parenteral DCT showing comparable efficacy as CEF, the gold-standard. The extended long-term pharmacokinetic activity of TLAe explains these results.

The posthatch prophylactic use of ceftiofur affects the cecal microbiota similar to the dietary sanguinarine supplementation in broilers.

The prophylactic administration of ceftiofur to newly hatched chicks is a common practice in some hatcheries worldwide to mitigate early gastrointestinal infections caused by Enterobacteriaceae. In spite of the crucial role of the gut microbiome for the broiler's health, there is still limited information on how the microbial composition is affected by such procedure. We investigated the effects of posthatch prophylactic application of ceftiofur on the cecal microbiota of 14-day-old broilers fed regular or sanguinarine-supplemented diets. DNA samples were extracted from cecal contents, amplified for the V3-V4 regions of the microbial 16S rRNA gene, and sequenced in a high-throughput sequencing platform (Illumina MiSeq). After downstream bioinformatics and statistical analyses, our results demonstrated that both ceftiofur and sanguinarine treatments similarly increased the proportions of the phylum Bacteroidetes and the genera Bacteroides and Megamonas, whereas reduced the relative abundances of Firmicutes and Lachnospiraceae in the ceca of the birds. Such changes are probably associated with increased carbohydrate fermentation processes favoring the production of short-chain fatty acids. This was also corroborated by the functional prediction findings, which suggest an increase in some metabolic pathways associated with digestibility in broilers receiving ceftiofur. Considering that antimicrobial stewardship in animal production systems is strongly needed to mitigate the threat of antimicrobial resistance, our findings show that supplementation with a phytogenic feed additive can lead to a similar microbial composition in the ceca of commercial broiler chickens, suggesting that the use of alternative products could lead to functional modifications without increasing pressure for antimicrobial resistance.

Detection of CTX-M-1 extended-spectrum beta-lactamase among ceftiofur-resistant Salmonella enterica clinical isolates of poultry.

Salmonella enterica resistance to extended-spectrum cephalosporins (ESC) conferred by cefotaximases (blaCTX-M) is a growing concern in the United States. Among food-producing animals, poultry are a major reservoir of ESC-resistant Salmonella. A retrospective study was carried out to further characterize 38 ceftiofur-resistant clinical Salmonella enterica isolates obtained from poultry during 2007-2018. Of the isolates tested, 31 displayed resistance to ceftriaxone and harbored blaCMY-2, whereas 7 isolates demonstrated resistance or reduced susceptibility to cefepime in addition to ceftriaxone resistance. These 7 isolates displayed extended-spectrum ß-lactamase activity, harbored blaCTX-M-1, and were recovered only from recent poultry diagnostic submissions made in 2011-2018 as opposed to the 31 isolates that were recovered in 2007-2018. Further characterization of the blaCTX-M-1 gene determined that it was located on conjugative IncN/ST1 and IncI1/ST87 plasmids in the isolates from commercial turkeys and broilers, respectively. These plasmids have been responsible for extensive spread of blaCTX-M-1 in livestock, poultry, and humans in Europe. Potential transfer of IncN and IncI1 plasmids and/or nontyphoidal Salmonella carrying these plasmids through the food chain, or by other means to humans, may result in treatment failures. Our study demonstrates the importance of further characterization of ceftiofur-resistant S. enterica isolates detected by veterinary diagnostic laboratories to identify the sources of blaCTX-M-1 and to mitigate the spread of ESC-resistant Salmonella in the poultry production pyramid.

Online fully automated SPE-HPLC-MS/MS determination of ceftiofur in bovine milk samples employing a silica-anchored ionic liquid as sorbent.

Solid-phase extraction coupled online with high performance liquid chromatography and tandem mass spectrometry was successfully applied to determine low concentrations of ceftiofur antibiotic in bovine milk samples. A silica-anchored ionic liquid was applied as sorbent material to be used as extraction phase in the proposed online system. The material was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. In order to improve the system reproducibility, the following experimental parameters were optimized: organic solvent percentage, time and sample loading flow rate. Subsequently, the method was validated presenting satisfactory results as adequate selectivity, good linearity and correlation coefficient higher than 0.98. The limit of detection and quantification were 0.1 and 0.7 µg/L, respectively. The precision of the methodology was evaluated as repeatability and intermediate precision, with relative standard deviation values lower than 15%. The accuracy of the method ranged from 72.8 to 137% and the minimum and maximum recovery values were 73.4 and 111.3%, respectively. After the validation, seven milk samples were analyzed and although ceftiofur was not detected in any of them the method was demonstrated to be efficient when applied to the analysis of milk samples fortified with the pollutant of interest.

Salmonella Heidelberg resistant to ceftiofur and disinfectants routinely used in poultry / Salmonella Heidelberg resistente ao ceftiofur e desinfetantes rotineiramente utilizados na avicultura

Bacteria of the genus Salmonella may infect humans and domestic animals, causing a serious public health problem worldwide. Nowadays, Salmonella enterica serovar Heidelberg (SH) is among the top three serovars isolated from people with salmonellosis and it is present in the poultry production chain. Moreover, it seems to be more invasive than other serotypes that cause enteritis. The overall status of the antimicrobial resistant of Brazilian strains of SH is still unknow. The bacterium may use similar mechanisms of resistance to antibotics, as well as disinfectants such as the efflux system and enzymatic degradation of chemical compounds. Thus, the objective of this study was to identify the Minimal Inhibitory Concentration (MIC) for ceftiofur of SH isolated from different materials of poultry origin, as well as to verify the relation between antibiotic resistance and disinfectant resistance. In addition, the screening efflux system was performed, using ethidium bromide to determine the presence of this mechanism of resistance. MIC results indicated high levels of SH resistance to ceftiofur, indicating the need for alternative drugs to treat salmonellosis. The concentration of ceftiofur needed to eliminate SHresistant isolates were 32 times higher than the therapeutic dose. Regarding disinfectants, most of the disinfectants tested were efficient to eliminate SH, however one isolate was resistant to glutaraldehyde-quaternary ammonia. All isolates were negatives in the screening efflux system, which suggest a different mechanism of resistance. It is possible to conclude that SH shows a real threat to poultry production, and caution should be taken when choosing the right antibiotic and disinfectant against this serovar.(AU)

Bactérias do gênero Salmonella podem infectar o homem e animais domésticos, causando sérios problemas de saúde pública no mundo todo. Hoje, a Salmonella enterica serovar Heidelberg (SH) está entre os três sorovares mais comumente isolados de pessoas com salmonelose, e presente na cadeia produtiva avícola. Além disso, SH parece ser mais invasiva que outros sorovares que causam enterite.O perfil geral de resistência aos antimicrobianos de cepas brasileiras de SH ainda é desconhecido. Esta bactéria parece usar mecanismos de resistência aos antibióticos similares aos usados para desinfetantes,tais como a bomba de efluxo e a degradação enzimática de compostos químicos. Por isso, o objetivo deste trabalho foi de identificar a Concentração Mínima Inibitória (CMI) para o ceftiofur de isolados de SH oriundas de produtos avícolas diversos, bem como de verificar a relação entre resistência a antibióticos e desinfetantes. Além disso, o sistema de bomba de efluxo foi realizado usando o brometo de etídio para determinar se esse era o mecanismo de resistência utilizado. Os resultados do MIC indicaram altos níveis de resistência para ceftiofur, demonstrando a necessidade de formas alternativas para o tratamento da salmonelose. Desinfetantes routineiramente utilizados pela indústria avícola foram eficientes no combate da SH, porém um isolado mostrou-se resistente ao desinfetante glutaraldeído associado à amônia quaternária. Todos os isolados foram negativos para o sistema de bomba de efluxo,sugerindo que há outro mecanismo de resistência envolvido. É possível concluir que os isolados brasileiros de SH representam uma ameaça para a avicultura, e cautela deveria ser tomada na hora da escolha do antibiótico e do desinfetante a ser utilizado contra este sorovar.(AU)

Salmonella Heidelberg resistant to ceftiofur and disinfectants routinely used in poultry / Salmonella Heidelberg resistente ao ceftiofur e desinfetantes rotineiramente utilizados na avicultura

Bacteria of the genus Salmonella may infect humans and domestic animals, causing a serious public health problem worldwide. Nowadays, Salmonella enterica serovar Heidelberg (SH) is among the top three serovars isolated from people with salmonellosis and it is present in the poultry production chain. Moreover, it seems to be more invasive than other serotypes that cause enteritis. The overall status of the antimicrobial resistant of Brazilian strains of SH is still unknow. The bacterium may use similar mechanisms of resistance to antibotics, as well as disinfectants such as the efflux system and enzymatic degradation of chemical compounds. Thus, the objective of this study was to identify the Minimal Inhibitory Concentration (MIC) for ceftiofur of SH isolated from different materials of poultry origin, as well as to verify the relation between antibiotic resistance and disinfectant resistance. In addition, the screening efflux system was performed, using ethidium bromide to determine the presence of this mechanism of resistance. MIC results indicated high levels of SH resistance to ceftiofur, indicating the need for alternative drugs to treat salmonellosis. The concentration of ceftiofur needed to eliminate SHresistant isolates were 32 times higher than the therapeutic dose. Regarding disinfectants, most of the disinfectants tested were efficient to eliminate SH, however one isolate was resistant to glutaraldehyde-quaternary ammonia. All isolates were negatives in the screening efflux system, which suggest a different mechanism of resistance. It is possible to conclude that SH shows a real threat to poultry production, and caution should be taken when choosing the right antibiotic and disinfectant against this serovar.

Bactérias do gênero Salmonella podem infectar o homem e animais domésticos, causando sérios problemas de saúde pública no mundo todo. Hoje, a Salmonella enterica serovar Heidelberg (SH) está entre os três sorovares mais comumente isolados de pessoas com salmonelose, e presente na cadeia produtiva avícola. Além disso, SH parece ser mais invasiva que outros sorovares que causam enterite.O perfil geral de resistência aos antimicrobianos de cepas brasileiras de SH ainda é desconhecido. Esta bactéria parece usar mecanismos de resistência aos antibióticos similares aos usados para desinfetantes,tais como a bomba de efluxo e a degradação enzimática de compostos químicos. Por isso, o objetivo deste trabalho foi de identificar a Concentração Mínima Inibitória (CMI) para o ceftiofur de isolados de SH oriundas de produtos avícolas diversos, bem como de verificar a relação entre resistência a antibióticos e desinfetantes. Além disso, o sistema de bomba de efluxo foi realizado usando o brometo de etídio para determinar se esse era o mecanismo de resistência utilizado. Os resultados do MIC indicaram altos níveis de resistência para ceftiofur, demonstrando a necessidade de formas alternativas para o tratamento da salmonelose. Desinfetantes routineiramente utilizados pela indústria avícola foram eficientes no combate da SH, porém um isolado mostrou-se resistente ao desinfetante glutaraldeído associado à amônia quaternária. Todos os isolados foram negativos para o sistema de bomba de efluxo,sugerindo que há outro mecanismo de resistência envolvido. É possível concluir que os isolados brasileiros de SH representam uma ameaça para a avicultura, e cautela deveria ser tomada na hora da escolha do antibiótico e do desinfetante a ser utilizado contra este sorovar.

Sonochemical synthesis of porous NiTiO3 nanorods for photocatalytic degradation of ceftiofur sodium.

Porous NiTiO3 nanorods were synthesized through the sonochemical route followed by calcination at various temperature conditions. Surface morphology of the samples was tuned by varying the heat treatment temperature from 100 to 600°C. The synthesized NiTiO3 nanorods were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, diffused reflectance spectroscopy, photoluminescence spectroscopy and Brunauer-Emmett-Teller (BET) analyses. The characterization studies revealed that the NiTiO3 nanomaterial was tuned to porous and perfectly rod shaped structure during the heat treatment at 600°C. The porous NiTiO3 nanorods showed visible optical response and thus can be utilized in the photocatalytic degradation of ceftiofur sodium (CFS) under direct sunlight. The photoluminescence intensity of the porous NiTiO3 nanorods formed while heating at 600°C was lower than that of the as-synthesized NiTiO3 sample owing to the photogenerated electrons delocalization along the one dimensional nanorods and this delocalization resulted in the reduction of the electron-hole recombination rate. The photocatalytic degradation of ceftiofur sodium (CFS) was carried out using NiTiO3 nanorods under the direct sunlight irradiation and their intermediate products were analysed through HPLC to deduce the possible degradation mechanism. The porous NiTiO3 nanorods exhibited an excellent photocatalytic activity towards the CFS degradation and further, the photocatalytic activity was increased by the addition of peroxomonosulfate owing to the simultaneous generation of both OH and SO4-.

Randomized clinical trial comparing ceftiofur hydrochloride with a positive control protocol for intramammary treatment of nonsevere clinical mastitis in dairy cows.

The objective of this study was to compare ceftiofur hydrochloride with a positive control protocol for intramammary treatment of nonsevere clinical mastitis in dairy cows. A total of 264 clinical mastitis cases on 11 commercial dairy farms were treated with intramammary infusions, once a day for 4 d using 1 of 2 treatments: (1) ceftiofur hydrochloride 125mg; or (2) control: tetracycline 200mg + neomycin 250mg + bacitracin 28mg + prednisolone 10mg. Streptococcus agalactiae was the most frequently isolated gram-positive pathogen from clinical mastitis, followed by Staphylococcus aureus. Klebsiella spp. and Escherichia coli were the most isolated gram-negative bacteria from clinical mastitis. No significant differences were observed between treatments regarding the overall clinical cure, bacteriological cure, and new infection. No effect of treatment regimen was observed when the bacterial group (gram-positive vs. gram-negative) was evaluated. The overall clinical cure was 0.79 for ceftiofur-treated cows and 0.74 for control-treated cows, whereas the overall bacteriological cure was 0.79 for ceftiofur-treated cows and 0.76 for control-treated cows. Furthermore, the new intramammary infection was 0.10 for cows treated with ceftiofur and 0.11 for cows treated with control. In conclusion, the use of intramammary ceftiofur hydrochloride for treatment of nonsevere clinical mastitis has similar efficacy as a treatment regimen with a combination of antimicrobial agents (tetracycline + neomycin + bacitracin).

Evaluación del efecto antimicrobiano Aloe barbadensis Miller asociado a ceftiofur o cloxacilina sobre cepas de Staphylococcus aureus / Evaluation of the antimicrobial effect Aloe barbadensis Miller associated with ceftiofur or cloxacillin on strains of Staphylococcus aureus

El uso excesivo de antimicrobianos, debido a la intensificación de los sistemas productivos, ha producido un aumento en la resistencia bacteriana. Debido a esto, diferentes organizaciones intergubernamentales han solicitado el uso racional de estos fármacos en estos sistemas productivos. El mal uso de antimicrobianos se observa en diversas patologías, dentro de las cuales se encuentra la mastitis clínica del ganado lechero, cuyo principal agente etiológico en la zona sur del país es Staphylococcus aureus, resistente a múltiples fármacos. Por este motivo se han estudiado nuevas alternativas terapéuticas, como Aloe vera, por su efecto antimicrobiano. Se evaluaron los efectos inhibitorios de liofilizados de geles de A. vera comercial y extraído de plantas nacionales, asociados a cloxacilina o ceftiofur frente a S. aureus ATCC 29213 mediante el Método de Macrodilución en Caldo. Se determinó su Concentración Mínima Inhibitoria (CMI) mediante turbidez y se confirmó por UFC/mL y absorbancia. Los resultados obtenidos demostraron una disminución de un 87,5% y 75% en las CMI establecidas por el CLSI de ceftiofur y cloxacilina respectivamente. Estos resultados permitirían formular un tratamiento intramamario con esta asociación para las mastitis clínicas causadas por S. aureus. Esto disminuiría la posibilidad de generar resistencia, como también reduciría los periodos de carencia definidos actualmente para estos fármacos.

Evaluación del efecto antimicrobiano de Aloe barbadensis Miller asociado a ceftiofur sobre cepas de Escherichia coli / Evaluation of the antimicrobial effect of Aloe barbadensis Miller associated with ceftiofur on strains of Escherichia coli

El uso indiscriminado de antimicrobianos en animales de producción es la principal causa del aumento de la resistencia bacteriana, por lo que organizaciones intergubernamentales solicitan disminuir el uso excesivo de estos fármacos. La mastitis es causada principalmente por Escherichia coli en la zona central de Chile y, debido a que su tratamiento se concentra en el uso de antimicrobianos, se ha estudiado Aloe barbadensis Miller (Aloe vera) como una alternativa terapéutica por su efecto antimicrobiano. El objetivo de este trabajo fue evaluar el efecto inhibitorio "in vitro" de A. vera asociado a Ceftiofur en concentraciones menores a su Concentración Mínima Inhibitoria (CMI), frente a E. coli ATCC 25922 y en cepas aisladas de vacas con mastitis clínica. Se utilizó el Método de Macrodilución en Caldo. La CMI fue determinada mediante turbidez y confirmada por recuento de UFC/mL y por espectrofotometría UV-visible. Las cepas de campo fueron sometidas a un estudio de sensibilidad (Kirby Bauer) frente a un panel de antimicrobianos antes de analizar el efecto inhibitorio de A. vera. La CMI de A. vera se determinó en 60 mg/mL. La asociación de A. vera/Ceftiofur no inhibió el crecimiento de E. coli ATCC 25922. Todas las cepas de campo presentaron sensibilidad intermedia o resistencia a al menos un antimicrobiano, pero fueron inhibidas por A. vera. Esto sugiere que A. vera es más efectiva en la inhibición del crecimiento de E. coli en comparación a la asociación y podría presentarse como una alternativa terapéutica frente a mastitis clínicas causadas por E. coli.

Ceftiofur-loaded PHBV microparticles: a potential formulation for a long-acting antibiotic to treat animal infections

Background: The infectious diseases in the livestock breeding industry represent a significant drawback that generates substantial economic loss and have led to the indiscriminate use of antibiotics. The formulation of polymeric microparticles loaded with antibiotics for veterinary use can: reduce the number of required doses; protect the drug from inactivation; and maintain a sustained-release of the antibiotic drug at effective levels. Accomplishing all of these goals would have a significant economic and animal health impact on the livestock breeding industry. Results: In this work, we formulated ceftiofur-loaded PHBV microparticles (PHBV-CEF) with a spherical shape, a smooth surface and diameter sizes between 1.65 and 2.37 μm. The encapsulation efficiency was 39.5 +/- 1.1 percent w/w, and we obtained a sustained release of ceftiofur in PBS-buffer (pH 7.4) over 7 days. The antibacterial activity of ceftiofur was preserved after the encapsulation procedure, and toxicity of PHBV-CEF microparticles evaluated by MTS was represented by an IC50 > 10 mg/mL. Conclusions: Our results suggest that PHBV-CEF particles have a potential application for improving the treatment of infectious diseases in the livestock breeding industry.